4x(-3+x)=2800

Solution for 4x(-3+x)=2800 equation:

4x(-3+x)=2800

We move all terms to the left:

4x(-3+x)-(2800)=0

We add all the numbers together, and all the variables

4x(x-3)-2800=0

We multiply parentheses

4x^2-12x-2800=0

a = 4; b = -12; c = -2800;
Δ = b2-4ac
Δ = -122-4·4·(-2800)
Δ = 44944
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{44944}=212$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-12)-212}{2*4}=\frac{-200}{8}
=-25
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-12)+212}{2*4}=\frac{224}{8}
=28
$